A short and incomplete introduction to scheduling in UNIX and Linux, and how tasks interact with the kernel.
A Memory Management talk by Rik van Riel
KernelMemoryAllocation: A brief overview of the different memory management mechanisms used in the kernel.
Copy from/to user-space implementation. A description of the x86 copy_from/to_user() core code.
Device driver infrastructure
Understanding The Linux Kernel Initcall Mechanism: How module_init() and friends work.
Linux IP Networking A description of Linux 2.2's IP stack, with diagrams.
Networking everything network related
A seq_file HOWTO Describes the seq_file API, used for outputting information via /proc.
Why Reiser4 is not in the Linux Kernel.
KernelPorts porting the kernel to other architectures
Read-Copy Update (RCU)
RCU Links to RCU documentation